new utility method

refs 163

org.fortiss.tooling.kernel/trunk/src/org/fortiss/tooling/kernel/utils/EcoreUtils.java

+/*--------------------------------------------------------------------------+
+$Id: codetemplates.xml 1 2011-01-01 00:00:01Z hoelzl $
+|                                                                          |
+| Copyright 2011 ForTISS GmbH                     |
+|                                                                          |
+| Licensed under the Apache License, Version 2.0 (the "License");          |
+| you may not use this file except in compliance with the License.         |
+| You may obtain a copy of the License at                                  |
+|                                                                          |
+|    http://www.apache.org/licenses/LICENSE-2.0                            |
+|                                                                          |
+| Unless required by applicable law or agreed to in writing, software      |
+| distributed under the License is distributed on an "AS IS" BASIS,        |
+| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
+| See the License for the specific language governing permissions and      |
+| limitations under the License.                                           |
++--------------------------------------------------------------------------*/
+package org.fortiss.tooling.kernel.utils;
+
+import org.eclipse.emf.common.util.BasicEList;
+import org.eclipse.emf.common.util.ECollections;
+import org.eclipse.emf.common.util.EList;
+
+/**
+ * Utility methods for dealing with .ecore models. These methods should be used
+ * to define EMF operations that make the models easier to use.
+ * 
+ * @author ratiu
+ * @author $Author: hoelzl $
+ * @version $Rev: 18709 $
+ * @ConQAT.Rating RED Hash:
+ */
+public class EcoreUtils {
+
+	/**
+	 * Converts an EList of a given type into an EList of one of its subtypes.
+	 * Utility method to avoid unnecessary casts.
+	 * 
+	 * @param targetClass
+	 *            - the class representing the subtype
+	 * @param sourceList
+	 *            - the source list containing objects of type S, a supertype of
+	 *            T
+	 * @return a target EList containing elements of type targetClazz
+	 */
+	@SuppressWarnings("unchecked")
+	public static <S, T extends S> EList<T> convertList(Class<T> targetClass,
+			EList<S> sourceList) {
+		return (EList<T>) (EList<?>) sourceList;
+	}
+
+	/**
+	 * From a given EList with source objects of type S create another
+	 * unmodifiable EList with objects of type T, whereby T is a sub-type of S.
+	 * The resulting EList is unmodifiable thereby it represents only a view
+	 * over the source list.
+	 * 
+	 * @param targetClass
+	 *            - a class representing type T
+	 * @param sourceList
+	 *            - an EList with objects of type S
+	 * @return an unmodifiable EList of objects of type T
+	 */
+	@SuppressWarnings("unchecked")
+	public static <S, T extends S> EList<T> pickInstanceOf(
+			Class<T> targetClass, EList<S> sourceList) {
+		if (sourceList == null)
+			return null;
+		EList<T> result = new BasicEList<T>();
+		for (S sourceElement : sourceList)
+			if (targetClass.isAssignableFrom(sourceElement.getClass()))
+				result.add((T) sourceElement);
+		return ECollections.unmodifiableEList(result);
+	}
+}